Elucidating Photo‐Kinetic Control in Photothermal Reverse Water‐Gas Shift Reaction

ABSTRACT Unlike the well‐known charge‐carrier kinetics in traditional photocatalysis, a knowledge gap remains regarding the photo‐kinetic effects in heterogeneous photothermal catalysis. Conventionally, light is mainly regarded as a source of charge carriers and localized heating, yet how these light‐induced effects alter intrinsic reaction kinetics, particularly the rate‐determining step (RDS), remains unclear. Here, we provide direct kinetic evidence that illumination tunes the RDS in an archetypal Mars‐van Krevelen (MvK) reverse water‐gas shift (RWGS) reaction over In‐doped MoO 2 . Under illumination, photogenerated electrons enrich In sites, promoting H 2 activation and spillover while accelerating H 2 O desorption, thereby shifting the RDS from the H 2 ‐reduction half‐reaction to the CO 2 ‐oxidation half‐reaction. This kinetic modulation significantly enhances catalytic performance and lowers the apparent activation energy. Overall, this work elucidates the kinetic role of light in photothermal CO 2 conversion, offering new insights into optimizing solar‐driven catalytic processes.